1. Field of the Invention
The present invention relates to a primer composition, and more specifically to a primer composition which effectively bonds silicone rubber to diverse substrates, particularly synthetic organic resins and metals.
2. Description of the Prior Art
Primers have heretofore been necessary for bonding silicone rubbers to various substrates such as, for example, plastics, glass, metal oxides, and metals. Various primers based on organofunctional silanes have been proposed to date.
However, in the case of substrates having an inert surface, such as plastics, primers based on typical organofunctional silanes are unsatisfactory because they do not achieve adequate adhesion between the silicone rubber and the substrate.
The present inventors conducted investigations in order to solve the aforementioned problem, and discovered that primer compositions containing certain organotitanate esters as the active ingredient effectively bond silicone rubbers to plastics, particularly organic resins. This type of primer, however, is not satisfactory for bonding silicone rubbers to metals. The present inventors also discovered that this disadvantage can be overcome by combining the organotitanate esters with specified classes of organosilicon compounds.
The object of the present invention is to provide primer compositions that effectively bond silicone rubbers to both plastics and metals.